One of the things that I once read in some Volvo literature about the audio
systems is that "every radio has a built-in equalizer where the sound curve
from the deepest bass to the highest treble is set separately to suit each
individual Volvo model." (This was in a long-gone Audio
Options brochure from from Volvo's Swedish web site -- it was in English. This document covered radios similar to ours which
are found in the European C70 models, so I'm going to assume that this
statement extends to the US-spec radios as well.) To add to this, my '99
Owner's Manual describes a five-band graphic equalizer that's built into
the (then) top of the line SC-901 stereo, and that equalizer has preset
curves available for the S70, V70 or both C70s. Those preset curves are
selected by holding down one of the preset buttons while powering up the
SC-901, but there's no similar function described for the SC-816 in my
car. Bummer!
Furthermore, the manual states that the SC-816 does have automatic loudness
compensation as well as "automatic sound compensation" (ASC). Loudness
compensation is a term typically used to describe boosting bass and treble
frequencies at low volume levels to compensate for the human ear's natural
insensitivity to those frequencies as sounds become softer. Most mid-range
or better home audio systems have a switch for such a feature, and many
car stereos do too. Our Volvo stereos apparently do not. The manual does
describe a way to turn the ASC function off. It sure would be nice if there
was a way to turn off the loudness, as well.
But maybe there is....
Several times recently, the subject has come up in a Brickboard
forum that there was some undocumented functionality built into the
controls of the SC-816. In summary, holding down the Chgr button while
powering up the stereo allows you to switch between "stereo reception compensation"
modes SRC1, SRC2, SRC3 and SRC4. I've since seen a Volvo Service
Bulletin for the SC-815 stereo -- very similar, also with AM/FM/Cassette
and CD -- which explains the use of a three position switch on the bottom
of the stereo that allows you to switch between low, normal and high multipath
sensitivity. (See the Volvo Service Bulletin for the 900 series vehicles
3-39-939, 10/95.) I can only speculate that this gives the equivalant of
a high-frequency stereo blend function that I've seen on some other tuners.
The idea is that, when reception gets weak, if the tuner designers minimize
the stereo separation at high frequencies, they can make the tuner slightly
more selective. This speculation is supported by the description of these
three settings on the SC-815 service bulletin:
L = low multi-path sensitivity provides high stereo reception. Recommended
in flat areas. (JR's note: I have a feeling that the word "reception"
should have been translated to "separation.")
N = Normal Position. Factory Setting.
H = High multi-path sensitivity gives low stereo reception and switches
to mono to keep interference to a minimum. Recommended in hilly areas.
Anyway, back to the SC-816. This stereo has four SRC modes, not three.
And, most significantly, the SC-816 controls this function via undocumented
modes of the front panel buttons. This led me to believe that there might
be other functions tucked away in this stereo. In yet another example of
how I have much too much time on my hands, I tested each and every one
of the SC-816's buttons while powering the unit on. Here's what I found:
Pressing and holding preset 1 while powering the stereo on will start
the volume at a moderately loud level. My best guess about this feature
is that it approximates a 90 db listening level. The speakers in the 70
series cars are all rated 90 db at 1 watt, so maybe this preset 1 function
is for setting the volume to some reference level for testing purposes.
Pressing and holding preset 4 while powering on will display a code
on the LCD panel. This code does not correlate to any serial number, model
number or any identification printed anywhere on my stereo, nor does it
correlate to the four digit security code for my particular stereo. On
my stereo, the code that is displayed is "07156." If yours is different,
or even if it's the same, I'd like to hear from you. Maybe there's some
correlation between models and years, so let me know what you're driving
if you write me. (This just in: one reader with the SC-815 stereo has a
code of 06155. Another reader with the SC-816 in his '98 S70 tells me that
his code was the same 07156 as mine.) My best guess is that this is the
zip code for where Jimmy Hoffa is burried. Zip codes matching the pattern
071xx are in the Newark/Irvington area of the meadowlands in NJ. The US
Postal Service web site doesn't list 07156 as a valid zip code, but you
know they wouldn't publish Jimmy Hoffa's zip code anyway. At least Jimmy
can get his mail. The big question is "how do the swedes know?" Hmmm....
:)
Pressing and holding preset number 5 when you turn the stereo on will
cause the display to show "USA" or "AUS" for the Australian market. When
the display is in this mode, pressing that same preset a second time will
switch to the other mode. As far as I could determine, this merely switches
the FM station separation from the US standard of 0.2 Mhz spacing to the
rest of the world's 0.1 MHz spacing. BTW, this frequency mode switching
is described in the regular S70 owners manual.
Some new functions appear after the stereo has been disconnected from
the battery:
Pressing and holding preset number 3 when you turn the stereo on will
activate all LCDs on the display. Pressing 3 again will toggle between
that state and another display, possibly in Japanese. (These stereos are
made by Mitsubishi for Volvo.)
Pressing and holding preset number 6 when you turn the stereo on will
allow the stereo to function for about 3 minutes, after which time the
stereo shuts off and resumes the security lockout function.
Pressing and holding the "auto" button when you turn on the stereo will
allow you to erase all station presets. When "erase" is displayed on the
LCD panel, pressing "auto" again will confirm the erase command.
All of the other presets and other buttons seem to have no additional
functionality on the SC-816. The equalizer settings on the SC-901 are accessed
by holding down preset 2 if I recall correctly, but again, this seems to
do nothing on the SC-816. But someone must know how to change the allegedly
built in equalizer on this stereo. The truth is out there... somewhere.
If anyone can reference any official Volvo documentation on the functions
of the "double secret stereo programming buttons," I'd love to hear from
you. I'm also trying to find trends in the factory SRC settings for each
model of car that the SC-816 is installed in. If you can add anything on
this subject, please
write me. If you give me good information, then I'll tell you which
dashboard switch has a secret start up function to enable 18 lbs of boost
on the T5 cars. ;) (click here for details)